This application requests a new state-of-the-art positron emission tomography scanner. This camera will extend and replace the current GE 4096+WB. The new scanner that we propose will have numerous capabilities that will greatly enhance the current research program. Our funded and pending research studies encompass multiple universities, institutes and schools within and outside Johns Hopkins University in the Baltimore area. Furthermore, there are on-going major international collaborations with PET scan sites with similar or identical machines to our scanner choice. The major focus of our research has historically involved the imaging of human and non-human primate CNS neuroreceptors including dopamine, serotonin, opiate, cholinergic and other receptor systems. These studies have spanned the entire age range from children with mental retardation through diseases of young adults such as schizophrenia and depression and drug abuse through studies in the elderly, including Alzheimer's and Parkinson's disease. All of these studies require the most exquisite 3D resolution and axial sampling to provide the maximum recovery of small structures with receptor binding tracers. Another major area is oncology, including studies of brain and whole body tumors, and measures of DNA synthesis. The proper quantification and development of these new techniques in oncology also require the high sensitivity and resolution available with new scanners. A third area that is of increasing interest is the measurement of regional cerebral blood flow in normal aging and with drug perturbations in various neuropsychiatric disorders such as schizophrenia. To examine subtle changes between various tasks also requires the best resolution. A more capable camera is essential for our new chemistry developments and new methodological approaches to be a productive as possible. A scanner of the newest generation will provide improved axial field of view, number of slices, improved inplane and axial resolution and sensitivity, all of which will dramatically impact on our research. All of these camera features will tremendously improve the interdisciplinary research which is ongoing at our Center.